Magazine for a firearm including a self-contained ammunition counting and display system

ABSTRACT

An ammunition clip or magazine for a firearm including a self-contained system for sensing the amount of ammunition contained within the magazine and visually indicating that value to the user of the firearm. The counting and display system may be configured to display the number of rounds remaining in the magazine itself, or the number of rounds remaining in the firearm overall (the number of ammunition rounds in the magazine plus one round in the chamber of the firearm, if applicable), or it may be configured to simply indicate that the magazine is empty or that the number of rounds remaining in the magazine is below some other predetermined threshold. The magazine may be utilized in conjunction with any suitable firearm without modifying the firearm.

FIELD OF INVENTION

The present invention relates to a magazine for a firearm, also known asa "clip", and more particularly to a magazine including a system forsensing the amount of ammunition contained within the magazine andvisually indicating that value to the user of the firearm. The countingand display system may be configured to display the number of roundsremaining in the magazine itself, or the number of rounds remaining inthe firearm overall (the number of ammunition rounds in the magazineplus one round in the chamber of the firearm, if applicable), or it maybe configured to simply indicate that the magazine is empty or that thenumber of rounds remaining in the magazine is below some otherpredetermined threshold.

BACKGROUND OF THE INVENTION

A common problem associated with the use of firearms, especiallyautomatic or semi-automatic firearms, is the inability of the user toeasily and accurately determine the number of ammunition roundsremaining in the magazine or "clip" of the gun. In certain lawenforcement and military situations for example, the law enforcementofficer or soldier may need to know the precise amount of ammunitionremaining in his or her weapon, or at the very least, that the number ofrounds remaining is below some predetermined threshold. Also, gunenthusiasts and hunters have found a need and a desire for easily andaccurately determining the number of live rounds of ammunition remainingin a weapon. A knowledge of the precise number of rounds remaining in aweapon, or an indication that live ammunition is present in the weaponis another safeguard to preventing accidental shootings.

Ammunition counting and display devices for firearms have been developedin an effort to provide law enforcement officers, military personnel,hunters, gun enthusiasts, and others with a mechanism for easily andaccurately counting and displaying the number of rounds fired from aweapon, or the number of unfired rounds remaining in the weapon.However, none of these prior devices has proven to be satisfactory foraccomplishing either of these tasks. These prior systems have generallybeen too complicated and have all required the firearm itself to bemodified in some manner to accept the device. Many of the prior systemshave required modifications to the grip, the slide mechanism, and themagazine mechanism of a weapon. Such modifications and complexinstallation requirements make it difficult and undesirable for many gunusers to utilize these devices. Also, some of the prior devices add anunacceptable amount of bulk and weight to the firearm, resulting in aweapon that is more difficult to holster, aim, and fire.

Many of these prior ammunition counting systems utilize the movement ofthe slide mechanism of the firearm relative to the body of the firearmto count the number of times the weapon has been fired. There areseveral disadvantages to this approach. Any modification of the slideassembly, especially by a less experienced gun user, increases thelikelihood of the slide assembly becoming jammed or otherwisemalfunctioning. Also, these prior system that increment or decrement acounter based upon the movement of the slide necessarily require thatthe number of rounds initially present in the firearm is properly sensedor entered by the user. For example, one prior system assumes that themagazine will always be fully loaded when it is initially inserted intothe weapon and therefore automatically sets the counter to "8" or someother predefined value. The counter is then decreased by "1" each timethe slide moves relative to the gun body. It can be seen that should themagazine be loaded with less than eight rounds of ammunition when it isinitially inserted in to the weapon, the number of rounds indicated onthe display would be inaccurate, resulting in a dangerous andpotentially deadly situation.

Another disadvantage with merely incrementing or decrementing a counterbased upon movement of the slide mechanism is that should the devicefail to properly sense the firing of the weapon, even once, the countwill be inaccurate from that point on.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide anammunition magazine for a firearm including a self-contained system foraccurately sensing and displaying the number of rounds of ammunitionremaining in the magazine.

It is another object of the present invention to provide an ammunitionmagazine for a firearm including a self-contained system for accuratelysensing and displaying the number of rounds of ammunition in the firearmoverall (the number of rounds in the magazine plus the round in chamberof the firearm).

It is a further object of the present invention to provide an ammunitionmagazine for a firearm including a self-contained system for accuratelysensing and displaying the number of unfired ammunition rounds in themagazine, wherein the firearm does not need to be modified to accept themagazine.

It is still another object of the present invention to provide anammunition magazine for a firearm including a self-contained system foraccurately sensing and displaying the number of unfired ammunitionrounds in the magazine, wherein the magazine and ammunition countingsystem do not interfere with the holstering and firing of the firearm.

Additional objects and advantages of the present invention will be setforth in the description which follows.

To accomplish the foregoing and other objects, the present inventioncomprises an ammunition magazine for use in a firearm, wherein themagazine includes a follower therein for supporting at least one roundof ammunition within the magazine and a spring for biasing the followertoward an open end of the magazine. The magazine also includes sensingmeans for sensing the position of the follower within the magazine andan electronic circuit for determining and displaying the number ofrounds of ammunition contained within the magazine based upon theposition of the follower.

As ammunition is fired from the firearm, unfired rounds are taken fromthe open end of the magazine into the chamber of the firearm while emptyammunition cartridges or shells are ejected from the firearm. Thefollower therefore moves upward under the force of the follower spring.The sensing means senses the new position of the follower and theelectronic circuit determines the number of rounds remaining in themagazine based upon the new position. The circuit includes a displayelement to be viewed by the gun user for displaying the number of roundsof ammunition remaining in the magazine. Alternatively, the numericdisplay element may be replaced by one or more indicator lamps or lightemitting diodes that indicate the number of rounds of ammunitionremaining in the magazine, or that the number of rounds has fallen belowsome predetermined threshold (for example, a red indicator light may beused to indicate that the magazine is empty). In the case where afirearm user fully loads the firearm, including the magazine and alsoinserts a round of ammunition into the chamber of the firearm, that usermay want to increase the displayed count of ammunition by one to accountfor the round in the chamber. The present invention may thereforecomprise means for consistently increasing the indicated amount ofammunition in the magazine by one to accurately indicate the number ofrounds in the firearm overall.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is perspective view of a firearm including an ammunition magazinein accordance with the present invention;

FIG. 2 is a side view in cross section of an ammunition magazine inaccordance with the present invention;

FIG. 3 is a rear view, partially in cross section and partially inelevation of the ammunition magazine shown in FIG. 2;

FIG. 4 is a schematic diagram of an electronic circuit that may beincorporated into an ammunition magazine in accordance with the presentinvention;

FIG. 5 shows a schematic view of an alternative embodiment of thepresent invention;

FIG. 6 is partial schematic view of an alternative embodiment of thepresent invention;

FIG. 7A is a partial perspective view of another alternative embodimentof an ammunition magazine in accordance with the present invention;

FIG. 7B is a partially schematic, partially perspective view of theammunition magazine shown in FIG. 7A;

FIGS. 8A and 8B are a top plan view and a side elevational view,respectively, of an insulated electrically conductive follower springthat may be utilized in conjunction with the ammunition magazine shownin FIGS. 7A and 7B.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.Referring specifically to FIGS. 1-4, an ammunition magazine inaccordance with the present invention, also known as a clip, is showngenerally at 10 as it may be used in conjunction with a firearm such asa semi-automatic handgun12 as shown. A magazine 10 in accordance withthe present invention may be used with any firearm designed to accept amagazine or "clip" such as automatic and semi-automatic handguns andrifles, shotguns, and any other suitable firearm. Magazine 10 comprisesa generally hollow upper storage portion 15 for containing a quantity oflive ammunition rounds 20 such as bullets, cartridges, or shells. A gunuser loads ammunition 20 into upper portion 15 of magazine 10 bypressing the cartridges or shells 20 downwardinto magazine 10 through agenerally open top portion 17 as is well known in the field of firearmsand ammunition magazines.

Hollow upper portion 15 of magazine 10 includes an ammunition follower25, which is slidably positioned within hollow upper portion 15, forsupporting the one or more rounds of ammunition 20 within upper portion15of magazine 10. Follower 25 is biased upward toward open top 17 ofmagazine10 by a follower spring 26, and as ammunition rounds 20 areloaded into magazine 10, follower 25 is forced downward toward lowerportion 16 of magazine, thereby compressing follower spring 26. Aftermagazine 10 is inserted into firearm 12, firearm 12 is cocked, causing around of ammunition 20 to be automatically removed through open top 17of magazine 10 and positioned within the firing chamber 13 of firearm.Follower 25 simultaneously moves upward under the force of followerspring 26, therebypositioning a new round of ammunition 20 at open top17 of magazine 10. At this point, if desired, magazine 10 may be onceagain removed from firearm12 and an additional round of ammunition 20may be inserted into open top portion 17 of magazine 10 before it isreinserted into firearm 12. Firearmmagazine 10 will then be completelyfull, and a live round of ammunition 20will also be present in chamber13. This state, when chamber 13 contains a live round of ammunition 20,and when magazine 10 is also fully loaded, will hereinafter be referredto as the "plus one" state.

When the firearm 12 is fired, the empty ammunition cartridge is ejectedfrom firing chamber 13, and a new round of ammunition 20 isautomatically taken from open top 17 of magazine 10 and positioned inchamber 13. Follower 25 moves upward under force of follower spring 26 adistance equal to the width of the round of ammunition 20 removed fromopen top 17 of magazine 10. Firearm 12 may be repeatedly fired in thismanner, and follower 25 will correspondingly move incrementally upwardas described. It can be seen therefore that the location of follower 25within hollow upper portion 15 of magazine 10 depends upon the number ofammunition cartridges 20 stored in magazine 10. It can also be seen thatfor any number of ammunition cartridges 20 loaded in upper portion 15 ofmagazine 10 (from zero to fully loaded) follower 25 will assume a uniqueposition within upper portion 15 of magazine 10.

As shown in FIGS. 2 and 3, lower portion 16 of magazine 10 is attachedto hollow upper portion 15 using fasteners such as screws 17, althoughany other suitable method of attachment may be utilized and iscontemplated herein. Alternatively, upper portion 15 and lower potion 16of magazine 10may be manufactured as an integral one-piece unit. Whenmagazine 10 is inserted into firearm 12, only the lower portion 16 ofmagazine 10 extendsfrom the lower butt portion 14 of the firearmhandgrip 19. Lower portion 16of magazine 10 includes a visual display 30which is preferably rearwardly facing (relative to the direction ofbullet travel from the firearm) so asto be easily viewable by the gunuser. Visual display 30 is preferably a two digit, seven-segment lightemitting diode (LED) display or a similar liquid crystal display (LCD).Visual display 30 is positioned and orientedsuch that a gun user caneasily read the numbers displayed thereon with thegun in a wide varietyof positions, including the aiming/firing position. As is discussed inmore detail below, display 30 is part of an electronic circuit meanscontained within lower portion 16 of magazine 10 for determining thenumber of rounds of ammunition 20 present in the magazine 10 based uponthe position of follower 25. The electronic circuit means isalsoconfigured to drive the display element 30 thereof such that the numberof rounds of ammunition 20 within magazine 10 is visually displayedtothe gun user.

Referring now also to FIG. 4, the first embodiment of the presentinventionis shown schematically at 10. Upper portion 15 of magazine 10includes sensing means, connected to an electronic circuit 40 (discussedfully below), for sensing the position of follower 25 within upperportion 15 ofmagazine 10. In the example shown in FIG. 4, the sensingmeans is provided,in part, by a plurality of contacts 42a-42l preferablycorresponding in number to the total number of rounds of ammunitioncapable of being loadedinto upper portion 15 of magazine 10. Eachcontact 42a-42l is electrically insulated from upper portion 15 ofmagazine 10 which is typically metallic. Follower 25, which ispreferably made of an electrically non-conductive material, alsoincludes a contact 44, which forms part of the sensing means for sensingthe position of follower 25, and which is preferably a spring-loadedsliding contact 44 which is designed to contactone of contacts 42a-42lwhen follower 25 is adjacent thereto. Spring-loadedcontact 44 includes aspring 45 which urges contact 44 into engagement withcontacts 42a-42l.Spring-loaded sliding contact 44 is electrically connected to groundusing a ground wire 27 or by insulating follower spring 26 and usingspring 26 to connect spring-loaded contact 44 to ground potential.Contacts 42a-42l are also preferably positioned in upperportion 15 ofmagazine 10 such that for any number of rounds of ammunition 20 loadedinto upper portion 15 of magazine 10, one contact 42a-42l will beadjacent to and contacted by sliding contact 44. This engagement ofsliding contact 44 with one of contacts 42a-42l at each discretelocation of follower 25 can be exploited in a variety of ways todetermine and display the number of rounds of ammunition 20 withinmagazine 10. In the example shown, contact 42a corresponds to theposition of follower 25 whenone round of ammunition 20 is present inupper portion 15 of magazine 10. Likewise, contacts 42b-42l correspondrespectively to the position of follower 25 when 2-12 rounds ofammunition 20 are present in upper portion15 of magazine 10. When upperportion 15 of magazine 10 is empty, follower 25 will be positioned atthe open top 17 of upper portion 15 (as is shown in phantom at 25), suchthat none of contacts 42a-42l will be connected tospring-loaded contact44, resulting in the digit "0" being displayed on display element 30.

As shown in FIG. 4, for example, an electronic circuit 40 is provided,preferably within lower portion 16 of magazine 10. As shown herein,circuit 40 includes a voltage source 46 such as one or more batteries. Aswitch 48 may be provided for selectively connecting voltage source 46to circuit 40. For example, switch 48 may be positioned such that it isclosed automatically when magazine 10 is inserted into firearm 12.Alternatively, switch 48 may be selectively activated by the gun user toconnect voltage source 46 to circuit 40 such that display 30 selectivelydisplays the number of rounds of ammunition within magazine 10. Whenswitch 48 is closed, voltage source 46 provides a voltage (Vcc) tocomponents of circuit 40.

Display 30, in the example shown, comprises two Panasonic LN524GK sevensegment LED display elements U3 and U4. As shown herein, display elementU3 must display the "ones" digit of the display 30 and consequently mustbe capable of displaying any digit 0-9. Input pins (11,10,8,6,5,12,7) ofdisplay element U3 (each being connected to and controlling one of theseven segments a-g of the display element) are therefore respectivelyconnected to output pins (13,12,11,10,9,15,14) of a 74HC4511 BinaryCoded Decimal (BCD) to seven segment decoder driver U2, or an equivalentthroughcurrent limiting 220 Ohm resistors 52. Display element U4 isdesigned to display the "tens" digit of display 30 and therefore isneeded only if magazine 10 has a capacity of greater than nine rounds ofammunition 20.

BCD to seven segment decoder driver U2 is connected to (Vcc) at inputpin 16, while input pins 5 and 8 thereof are tied to ground to establisha logic "low", and input pins LT and BI are pulled to logic "high" byconnection to Vcc through a 1 Megohm "pull-up" resistor 50. DecoderdriverU2 includes four logic inputs (A,B,C,D) which correspondrespectively to BCD bits 2⁰,2¹,2²,2³ such that, for example, when inputsA and D of decoder driver U2 are at a logic level "high" and inputsB andC of decoder driver U2 are at a logic "low" (indicating a value of 2⁰+2³ at the inputs (A,B,C,D), decoder driver U2 will establishthe properlogic voltage levels at its output pins (13,12,11,10,9,15,14) such thatthe decimal value corresponding to the BCD value of 2⁰ +2³, which is 9,is displayed by display element U3. Each logic inputpin (A,B,C,D) ofdecoder driver U2 is respectively tied to (Vcc) through aninverterU1a-U1d, each of which inverters U1a-U1d is preferably provided aspartof an inverter chip package U1 consisting of 6 inverters U1a-U1f, suchasan MM74HC14 Hex Inverting Schmitt Trigger, and the respective input pin(13,5,3,1) each a inverter U1a-U1d is initially pulled to a logic "high"by connection to (Vcc) through 1 Megaohm pull-up resistors 50. Inverterpackage U1 is tied to Vcc at input pin 14 thereof and to ground atoutput pin 7 thereof.

Display element U4 will preferably be blank or will display the digit"1" as required, and therefore its connection to the remainder ofcircuit 40 is more simple than the connection of display element U3.However, those skilled in the art will recognize that display element U4may be connectedin a manner similar to display element U3, or anequivalent manner, to display any digit "0"-"9". As shown in FIG. 4,element U4 has input pins 3and 15, which are connected to and controlsegments b and c thereof, connected through current limiting resistors52 to inverters U1e,U1f, respectively, each of which inverters U1e,U1fis also preferably provided as a part of inverter package U1. Therespective input pins 11,9 of inverters U1e,U1f are connected to (Vcc)through a 1 Megaohm pull-up resistor 50 to establish a logic "high" atinputs 9,11, thereby also establishing a logic "low" voltage level attheir respective outputs 8,10 and inputs 3,15 of display element U4(assuming less than 9 rounds of ammunition 20 are present in upperportion 15 of magazine 10).

Referring again to upper portion 15 of magazine 10, it can be seen thateach contact 42a-42l is tied to the cathode of at least one diode(D1-D21). The anode of each diode (D1-D21) is to tied to an input(1,3,5,13,9,11) of inverters (U1a,U1b,U1c,U1d,U1f,U1e). It can be seenthat, for example, contact 42a will be contacted by spring-loadedcontact 44 of follower 25 when one round of ammunition 20 is present inmagazine 10. In order to display a "1" on display element U3 whenfollower 25 is inthis position as described, input A of BCD decoderdriver U2 must be a logic "high" requiring the input 13 of inverter U1ato be pulled "low". The remaining inputs (B,C,D) of decoder driver U2should remain low, and therefore, the inputs (5,3,1) to their respectiveinverters U1b-U1d need to remain "high". Consequently, contact 42a mustonly be tied to one diodeD1. Anode of diode D1 is tied to input 13 ofinverter U1a such that when spring-loaded sliding contact 44 of follower25 is adjacent to and contacting contact 42a, thereby pulling input 13of inverter U1a to a reference potential or logic "low" voltage, input Aof decoder driver U2 will be pulled "high" by virtue of its connectionto output pin 12 of inverter U1a causing a "1" to be displayed ondisplay element U3. The remaining contacts 42b-42i are likewiseconfigured and connected to inputs1,3,5,13 of inverters(U1d,U1c,U1b,U1a) such that the required inputs 1,3,5,13 of inverters(U1d,U1c,U1b,U1a) are pulled "low" due to a connection betweenspring-loaded contact 44 and one of contacts 42b-i. As is discussedabove, one or more diodes D1-D16 are connected between contacts 42a-42isuch that current flows from (Vcc) to ground through pull-up resistors50 when contact is made between spring-loaded contact 44and one ofcontacts 42a-42i. Using the particular configuration shown in FIG. 4,the number of diodes that need to be connected to each contact 42a-42iis equal to the number of connections needed between each contact42a-42i and inputs (1,3,5,13) of inverters (U1d,U1c,U1b,U1a). Thoseskilled in the art will recognize that the number of connections neededbetween each contact 42a-42i and inputs (1,3,5,13) of inverter packageU1 is equal to the number of "1" bits needed in the BCD bit pattern foreach digit ("1"-"9" respectively) that must be displayed by displayelement U3.As another example, shown in FIG. 4, follower 25 will beadjacent to contact 42h when 8 rounds of ammunition 20 are present inmagazine 10 (only one round of ammunition 20 is shown). The digit "8" isencoded in BCD as "1000" which represents 2³. Therefore, the onlyinverter of package U1 that needs to be affected is U1d. Electricalconnection betweenspring-loaded contact 44 and contact 42h pulls inputpin 1 of inverter U1d to a logic "low" voltage state, thereby causinginput D of decoder displaychip U2 to be pulled "high". The input pins(A,B,C) of decoder driver U2 will not be affected and will remain "low".Therefore, decoder driver chipU2 will cause the value of 2³ or "8" to bedisplayed on display element U3. In general therefore, it can be seenthat for each position offollower 25 within upper portion 15 of magazine10, a unique input voltage pattern to circuit 40 will be provided fromthe sensing means such as contacts 44 and 42a-42l. Circuit 40 caninterpret each unique voltage pattern as discussed above to display thenumber of rounds of ammunition 20 present in magazine 10.

When more than 9 rounds of ammunition 20 are present in magazine 10,display element U4 must be utilized to provides a "tens" digit to thedisplay 30. In the example shown, display element U4 will remain blankwhen 0-9 rounds of ammunition 20 are present within magazine 10.However, in a manner similar to that described above in relation todisplay elementU3, display element U4 will display the digit "1" whenfollower 25 is adjacent to any of contacts 42j-42l as will occur in thepresent example when magazine 10 contains 10, 11, or 12 rounds ofammunition 20, respectively. It can be seen that each contact 42j-42lmust also be connected to the appropriate input pins 1,3,5,13 ofinverter package U1, as is discussed above, to cause the proper "ones"digit to be displayed simultaneously with the tens digit "1". Contact42j, which will be contacted by spring-loaded contact 44 when 10 roundsof ammunition 20 are present in magazine 10 is not connected to any ofthe input pins (1,3,5,13) of inverter package U1 because, when 10 roundsof ammunition 20are present in magazine 10, the "ones" digit that needsto be displayed is "0". Each contact 42j-42l must also be connected toinput pins 9,11 of inverter package U1. Inputs 9,11 of inverter packageU1 are also connectedto (Vcc) through a common 1 Megaohm pull-upresistor 50 to establish an initial logic voltage value of "high" atinputs 9,11 of inverter package U1, and consequently establish a logic"low" voltage level at outputs 8,10of inverter package U1 and alsoinputs 3,15 of display element U4 so that display element U4 willinitially be blank. However, when spring-loaded contact 44 of follower25 contacts a contact 42j-42l, thereby completing acircuit between (Vcc)and ground through a pull-up resistor 50, both inputs9,11 of inverterpackage U1, along with the appropriate "ones digit" input pins 1,3,5,13of inverter package U1, will be pulled to a logic "low" voltagepotential. This will cause both inputs 3,15 of display element U4 to bepulled high, resulting in the digit "1" being displayed thereon. Also,the relevant inputs (A,B,C,D) of decoder driver U2 will be pulled toalogic "high" voltage level so that the appropriate "ones" digit issimultaneously displayed on display element U3.

By preventing the reverse flow of current from each contact 42a-42l,diodesD1-D21 allow each contact 42a-42l to be multiplexed or connectedto more than one input (1,3,5,13,9,11) of inverter package U1. Forexample, as shown in FIG. 4, when 8 rounds of ammunition 20 are presentin magazine 10, input pin 1 of inverter U1d is pulled "low" by virtue ofthe connection between contacts 44,42h. Without the presence of diodeD16, input pin 1 of inverter U1d would be pulled back to "high" due tothe connection of contact 42i with input pin 1 of inverter U1d, and alsowith (Vcc) at input 13 of inverter U1a. Diodes D1-D21 also stoperroneous readings by preventing the metallic ammunition cartridges 20stacked on follower 25 (only one shown) from accidentally establishingan improper voltage level at one of the inputs (1,3,5,13) of inverterpackage U1. For example, as is shown in FIG. 4, a voltage potential(Vcc) exists at all contacts except 42h which is grounded. If a metallicammunition cartridge 20 was to contact any contact 42a-42g,42i-42l, thatammunition cartridge 20 and any others touching it would be connected to(Vcc). If a second contact 42a-42g, 42i-42l was then contacted by ancharged ammunition cartridge 20, an improper voltage level at inputs(1,3,5,13) of inverter package U1 could result. Diodes D1-D21 thereforeprevent a voltage potential from being established at inputs 1,3,5,13 byvirtue of their connection to an accidentally charged round ofammunition 20 and contact 42a-42l. Also, those skilled in the art willrecognize that an ammunition magazine 10 in accordance with the presentinvention may be provided with a switch for consistently increasing thedisplayed value by one so that a gun user can selectively increase thedisplayed number of rounds of ammunition 20 in the firearm 12 by one toaccount for the situation where the firearm includes a fully loadedmagazine 10 as well as a round of ammunition 20 in the chamber, or anyother situation where the gun user desires that the total number ofrounds of ammunition 20 in the firearm 12be displayed, rather thansimply the number of rounds of ammunition 20 in the magazine 10.

A simplified embodiment of the present invention is shown schematicallyat 10' in FIG. 5 wherein upper portion 15' of magazine 10 iselectrically connected to ground potential as shown and follower 25 isequipped with a spring-loaded contact 44 which is electrically tied toan electronic circuit 40' through an electrical current conducting pathsuch as a wire 27. Alternatively, as is shown in FIG. 6, metallicfollower spring 26' maybe insulated with any suitable insulatingmaterial 28 to form an electricalcurrent path 27 to circuit 40' suchthat spring-loaded contact 44 may be electrically connected to circuit40' directly through follower spring 26'. Although not required,follower spring 26' may be specially shaped tominimize contact withmetallic upper portion 15 of magazine 10, such that friction betweeninsulation 28 of spring 26' and upper region 15' of magazine 10 isminimized. Insulation 28 may be provided in any suitable form, and it isthought preferable to provide insulation 28 in one or morecylindricalplastic or similar segments as shown rotatably positioned around spring26' to further minimize friction between insulation 28 and upper portion15' of magazine 10'. In all other respects, magazine 10' shown in FIG.5, and that partially shown in FIG. 6 are identical.

Referring then to lower portion 16' of magazine 10', it can be seen thatlower portion 16 includes an electrical circuit 40' including a displayelement 30' designed to indicate to the gun user when the level ofammunition 20 within upper portion 15' of magazine 10' has dropped belowapredetermined level or threshold. Circuit 40' preferably includes oneor more switches 48a,48b such that a gun user can selectively controlthe operation of circuit 40'. For example, one of switches 48a,48b canbe positioned and configured to close automatically when magazine 10' isinserted into firearm 12, and the other of switches 48a,48b can beoperable by the gun user to selectively operate circuit 40'. In thismanner, circuit 40' will be inoperable unless magazine 10' is properlyinserted into firearm 12. In the example shown, display element 30' isprovided by an LED which will turn on and off (illuminate or extinguish)depending upon the number of rounds of ammunition 20 present in upperportion 15' of magazine 10'.

In general, it can be seen that spring-loaded contact 44 moves up anddown within upper portion 15 of magazine 10' in conjunction withfollower 25. Spring-loaded contact 44 includes a spring 45 whichconstantly urges contact 44 toward inner wall 18 of upper portion 15'.Inner wall 18 includes an exposed portion which acts as a second contactand those skilled in the art will recognize that any time contact 44touches an exposed portion of wall 18 (or any other non-insulated partof upper portion 15') circuit 40' will be completed (assuming switches48a,48b are closed) thereby providing an alternative means for sensingthe position offollower 25 within upper portion 15' of magazine 10'.When circuit 40' is completed, LED 30' will illuminate. A currentlimiting resistor 53 is provided in circuit 40' to prevent excessivecurrent from flowing therethrough. Therefore, as shown in FIGS. 5 and 6,an insulator material such as insulating strip 43 is positioned along aninterior portion of wall 18 of upper portion 15' of magazine 10' toselectively prevent contact 44 from contacting wall 18. In the exampleshown, it can be seen that LED 30' will remain unlighted any time upperportion 15' contains sufficient rounds of ammunition 20 such thatfollower 25 is pushed downward within upper portion 15' so that it isadjacent to insulator strip 43. As rounds of ammunition 20 are emptiedfrom upper portion 15', follower 25 is pushed upward by follower spring26'. It can therefore be seen that contact 44 will contact wall 18 atsome predefined point where strip 43 ends, and wall 18 is exposed. Asshown, LED 30' will illuminate when upper portion 15' is approximatelyhalf empty. However, by changing the length of insulating strip 43, anyother predetermined illumination point can be defined. For example,insulating strip 43 can be sufficientlylong such that LED 30' will notilluminate until upper portion 15' of magazine 10' is empty. Also,magazine 10' can be configured where LED 30' is normally illuminated andbecomes extinguished at a certain predefined level of ammunition 20.

FIGS. 7A and 7B show a further variation of a magazine in accordancewith the present invention at 10" which is closely related to magazine10' wherein follower 25 includes two spring-loaded contact 44a,44b, eachrespectively connected to a separate LED 30a",30b" using currentconducting wires 27. As is shown most clearly in FIG. 7B, inner wall 18ofupper portion 15" includes an insulation strip 43 which is shaped andpositioned such that spring-loaded contacts 44a,44b will contact wall 18at various different positions of follower 25 within upper portion 15".LED's 30a",30b" are therefore preferably different in color such thatthe gun user can easily distinguish therebetween. In the example shown,it canbe seen that both LED's 30a",30b" will remain unlighted whenmagazine 10" is full or nearly full and follower 25 is positionedapproximately in the lower half of magazine 10". As rounds of ammunition20 are taken from magazine 10", follower 25 will move upward aspreviously discussed. Insulating strip 43 is shaped such that when upperportion 15" of magazine10" is approximately half empty, spring-loadedcontact 44b will be moved into contact with wall 18 thereby completing apath for electrical currentto flow through LED 30b". As follower 25continues to move upward to a point where upper portion 15" is emptiedof ammunition 20, spring-loaded contact 44b will once again be preventedfrom contacting wall 18 due to the placement of insulating strip 43(causing LED 30b" to extinguish), while spring-loaded contact 44a willbe able to contact wall 18 due to thelack of any insulating strip 43adjacent to contact 44a when follower 25 isat the uppermost position,thereby lighting LED 30a" and indicating to the gun user that magazine10" is empty.

As is shown in FIGS. 8A and 8B, insulated follower spring 26" may beused in conjunction with the magazine 10" as an alternative to wire 27to connect spring-loaded contacts 44a,44b with circuit 40" in a mannersimilar to that described in relation to insulated spring 26'. Becausefollower 25 of magazine 10" includes two separate spring-loaded contact44a,44b, follower spring 26" includes two separate current conductingpaths 27a,27b which are insulated from one another and from upperportion 15" of magazine 10" by insulators 28.

It can be seen from the foregoing that the present invention provides anammunition magazine for a firearm including a self-contained system foraccurately sensing and displaying the number of ammunition roundsremaining in the magazine, without requiring the firearm to be modified.Those skilled in the art will recognize that various modifications canbe made to the present invention as disclosed herein without departingtherefrom. For example, any mechanical contacts could easily be replacedusing Hall effect sensors or optical means for sensing the position ofthefollower within the ammunition magazine. Also, any wired connectionscould be replaced with wireless connections such as optical, sonic,radio frequency, or other similar wireless connections. A wide varietyof different electrical components and connections may be utilized inaddition to the particular preferred embodiments as disclosed herein. Ingeneral, the foregoing description has set forth the preferredembodiment of the invention in particular detail and it must beunderstood that numerous modifications, substitutions and changes can beundertaken without departing from the true spirit and scope of thepresent invention as defined by the ensuing claims.

What is claimed is:
 1. An ammunition magazine for a firearm, saidmagazine comprising:an upper portion for containing at least one roundof ammunition, said upper portion of said magazine including anammunition follower movably positioned therein for supporting said atleast one round of ammunition within said upper portion of saidmagazine, said upper portion of said magazine also including a followerspring for biasing said follower toward an end of said upper portion ofsaid magazine; sensing means provided as a part of said ammunitionmagazine for sensing the position of said follower within said upperportion of said magazine; and, a circuit, including a display element,said circuit provided as a part of said ammunition magazine andconnected to said sensing means for determining and displaying to afirearm user information regarding the number of rounds of ammunition insaid upper portion of said magazine based upon the position of saidammunition follower within said upper portion of said magazine, wherebysaid ammunition magazine provides a self-contained ammunition countingand display system, independent from a firearm.
 2. An ammunitionmagazine as recited in claim 1, wherein said sensing means comprises atleast one first contact connected to said ammunition follower to bemovable therewith, and at least one second contact within said upperportion of said magazine, wherein said at least one first contact andsaid at least one second contact connect with one another at apredefined location of said follower within said upper portion of saidmagazine, thereby causing said display element of said circuit means todisplay a visual indication regarding the number of rounds of ammunitionpresent in said magazine.
 3. An ammunition magazine as recited in claim2, wherein said at least one second contact is provided by an exposedportion of an inner metallic wall of said upper portion of saidmagazine, and wherein said upper portion of said magazine furthercomprises an insulating strip to selectively prevent said at least onefirst contact from contacting said exposed portion of said inner wall.4. An ammunition magazine as recited in claim 3, wherein said firstcontact is provided by a spring-loaded contact including a spring forurging said first contact into engagement with said inner metallic wall.5. An ammunition magazine as recited in claim 2, wherein said displayelement of said circuit comprises at least one light emitting diode forilluminating when said at least one first contact engages said at leastone second contact.
 6. An ammunition magazine as recited in claim 2,wherein said at least one follower spring is insulated, and wherein saidat least one follower spring is connected to said at least one firstcontact such that at least one current conducting path is definedthrough said follower spring.
 7. An ammunition magazine as recited inclaim 1, wherein said sensing means comprises a first contact connectedto said ammunition follower to move therewith within said upper portionof said magazine, and comprises a plurality of second contactspositioned at predetermined locations within said upper portion of saidmagazine, such that said first contact connects with one of said secondcontacts when said follower is adjacent thereto.
 8. An ammunitionmagazine as recited in claim 7, wherein said display element of saidcircuit is provided by at least one seven-segment display.
 9. Anammunition magazine as recited in claim 7, wherein said first contact ofsaid sensing means is provided by a spring-loaded contact.
 10. Anammunition magazine as recited in claim 8, wherein said seven-segmentdisplay is driven by a decoder driver including a plurality of logicinput pins, and wherein each of said plurality of second contacts isconnected to at least one of said logic input pins, such that contactbetween said first contact and one of said plurality of second contactscauses said seven-segment display to display a numeric digit.
 11. Anammunition magazine as recited in claim 7, wherein said at least onefollower spring is insulated and a current conducting path from saidfirst contact is defined therethrough.
 12. An ammunition magazine asrecited in claim 10, wherein each of said plurality of second contactsis further connected to a voltage source such that a first voltage levelis established at each of said logic input pins to said decoder driver,and such that contact between said first contact and one of saidplurality of second contacts causes said first voltage level to changeto a second voltage level for at least one of said logic input pins ofsaid decoder driver.
 13. An ammunition magazine as recited in claim 10,wherein each of said plurality of second contacts is connected to atleast one of said logic input pins of said decoder driver through adiode, wherein each of said plurality of second contacts is connected toa cathode of said diode, and each of said logic input pins of saiddecoder driver is connected to an anode of said diode.
 14. An ammunitionmagazine as recited in claim 8, wherein said display element of saidcircuit displays a two-digit value representing the number of rounds ofammunition present in said ammunition magazine, wherein said displayelement comprises a first seven-segment display element for displaying aones digit, and a second seven-segment display element for displaying atens digit.
 15. An ammunition magazine comprising:a hollow upper portionfor containing a plurality of rounds of ammunition; a follower slidablydisposed within said hollow upper portion; a follower spring for biasingsaid follower toward an end of said upper portion; a circuit, includinga display element, for determining and displaying the number of roundsof ammunition in said upper portion of said magazine; and, sensing meansconnected to said circuit for sensing the position of said followerwithin said upper portion of said magazine, said circuit and saidsensing means being self-contained as a part of said ammunitionmagazine, separable from and independent of a firearm.
 16. An ammunitionmagazine as recited in claim 15, wherein said sensing means is providedby:a first contact connected to said follower to move therewith; and aplurality of second contacts positioned at predetermined locationswithin said upper portion of said magazine, each of said plurality ofsecond contacts connected to said circuit; whereby, for at least oneposition of said follower within said upper portion of said magazine, atleast one of said plurality of second contacts will be connected to saidfirst contact, thereby establishing a unique input voltage pattern tosaid circuit such that said circuit determines and displays visualinformation relating to the number of rounds of ammunition presentwithin said upper portion of said magazine based upon said unique inputvoltage pattern.